WORLD HEALTH ORGANIZATION GENEVA
Guidelines for
safe recreational water environments
VOLUME 1
COASTAL AND FRESH WATERS
GUIDELI NES FOR SAFE RECREA TI ONAL W A TER ENV IR ONMENTS VOL U ME 1. CO AS TAL AND FRESH WA TERS
ISBN 92 4 154580 1
The World Health Organization’s (WHO) new Guidelines for Safe Recreational Water Environments describes the present state of knowledge regarding the impact of recreational use of coastal and freshwater environments upon the health of users – specifically drowning and injury, exposure to cold, heat and sunlight, water quality (especially exposure to water contaminated by sewage, but also exposure to free- living pathogenic microorganisms in recreational water), contamination of beach sand, exposure to algae and their products, exposure to chemical and physical agents, and dangerous aquatic organisms. As well, control and monitoring of the hazards associated with these environments are discussed.
The primary aim of the Guidelines is the protection of public health. The Guidelines are intended to be used as the basis for the development of international and national approaches (including standards and regulations) to controlling the health risks from hazards that may be encountered in recreational water environments, as well as providing a framework for local decision-making. The Guidelines may also be used as reference material for industries and operators preparing development projects in recreational water areas, as a checklist for understanding and assessing potential health impacts of recreational projects, and in the conduct of environmental impact and environmental health impact assessments in particular.
WHO
Guidelines for safe
recreational water environments
VOLUME 1: COASTAL AND FRESH WATERS
WORLD HEALTH ORGANIZATION 2003
WHO Library Cataloguing-in-Publication Data World Health Organization.
Guidelines for safe recreational water environments. Volume 1, Coastal and fresh waters.
1.Bathing beaches—standards 2.Fresh water—microbiology 3.Water quality—analysis 4.Water pollution—analysis 5.Environmental monitoring—methods 6.Wound and injuries—prevention and control 7.Drowning 8.Risk management 9.Reference values 10.Guidelines I.Title II.Title: Coastal and fresh waters.
ISBN 92 4 154580 1 (NLM classification: WA 820)
© World Health Organization 2003
All rights reserved. Publications of the World Health Organization can be obtained from Marketing and Dissemination, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel: +41 22 791 2476; fax: +41 22 791 4857; email:
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The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recom- mended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omis- sions excepted, the names of proprietary products are distinguished by initial capital letters.
The World Health Organization does not warrant that the information contained in this publication is complete and correct and shall not be liable for any damages incurred as a result of its use.
Designed by minimum graphics Typeset in Hong Kong Printed in Malta
Contents
iii
List of acronyms and abbreviations vii
Preface ix
Acknowledgements xiii
Executive summary xix
CHAPTER 1. INTRODUCTION 1
1.1 General considerations 2
1.2 Types of recreational water environment 3
1.3 Types of use 4
1.4 Types of user 5
1.5 Hazard and risk 5
1.6 Measures to reduce risks in water recreation 11
1.7 Managing recreational waters 12
1.8 Nature of the guidelines 16
1.9 References 19
CHAPTER 2. DROWNING AND INJURY PREVENTION 20
2.1 Drowning 20
2.2 Spinal injury 23
2.3 Brain and head injuries 26
2.4 Fractures, dislocations and other minor impact injuries 26
2.5 Cuts, lesions and punctures 26
2.6 Interventions and control measures 27
2.7 Monitoring and assessment 30
2.8 References 31
CHAPTER 3. SUN, HEAT AND COLD 36
3.1 Exposure to ultraviolet radiation 36
3.2 Exposure to cold 45
3.3 Exposure to heat 47
3.4 References 48
CHAPTER 4. FAECAL POLLUTION AND WATER QUALITY 51
4.1 Approach 51
4.2 Health effects associated with faecal pollution 53 4.3 Approaches to risk assessment and risk management 57
4.4 Guideline values 63
4.5 Assessing faecal contamination of recreational water environments 75 4.6 Classification of recreational water environments 83
4.7 Management action 93
4.8 References 96
CHAPTER 5. FREE-LIVING MICROORGANISMS 102
5.1 Human pathogenic Vibriospecies 102
5.2 Aeromonasspecies 105
5.3 Free-living amoebae 106
5.4 Leptospiraspecies 110
5.5 Guideline values 111
5.6 Risk assessment and control measures 111
5.7 References 113
CHAPTER 6. MICROBIAL ASPECTS OF BEACH SAND QUALITY 118
6.1 Microorganisms in beach sand 118
6.2 Dispersion and fate of microorganisms in beach sand 121
6.3 Guideline values 123
6.4 Research and monitoring 123
6.5 Management actions 124
6.6 References 124
CHAPTER 7. ALGAE AND CYANOBACTERIA IN COASTAL AND
ESTUARINE WATERS 128
7.1 Exposure through dermal contact 128
7.2 Exposure through ingestion (of water or scum) 129
7.3 Exposure through inhalation 130
7.4 Identification of marine toxic algae and cyanobacteria 130
7.5 Guideline values 131
7.6 Precautionary measures 131
7.7 References 133
CHAPTER 8. ALGAE AND CYANOBACTERIA IN FRESH WATER 136
8.1 Occurrence of toxic cyanobacteria 137
8.2 Formation of cyanobacterial blooms 137
8.3 Cyanotoxins 138
iv GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
8.4 Evidence for toxicity of cyanobacteria 143
8.5 Evidence for toxicity of algae 146
8.6 Health risk evaluation 147
8.7 Guideline values 149
8.8 Management options 152
8.9 References 154
CHAPTER 9. AESTHETIC ISSUES 159
9.1 Aesthetic parameters 159
9.2 Economic consequences 162
9.3 Marine debris monitoring 163
9.4 Guideline values and management 165
9.5 References 166
CHAPTER 10. CHEMICAL AND PHYSICAL AGENTS 168
10.1 Exposure assessment 168
10.2 Hydrogen ion concentration (pH) 169
10.3 Dissolved oxygen 169
10.4 Chemical contaminants 169
10.5 Guideline values 170
10.6 Approach to assessing chemical hazards in recreational waters 171
10.7 References 172
CHAPTER 11. DANGEROUS AQUATIC ORGANISMS 173
11.1 Disease vectors 175
11.2 “In-water” hazardous organisms 177
11.3 “Water’s-edge” hazardous organisms 179
11.4 Venomous invertebrates 181
11.5 Venomous vertebrates 184
11.6 References 186
CHAPTER 12. MONITORING AND ASSESSMENT 189
12.1 Design and implementation of monitoring programmes 189
12.2 Aspects relevant to specific hazards 193
12.3 Progressive implementation of monitoring and assessment 196
12.4 References 198
CHAPTER 13. APPLICATION OF GUIDELINES AND MANAGEMENT OPTIONS FOR
SAFE RECREATIONAL WATER USE 199
13.1 Application of guidelines 199
13.2 Recreational water safety plan 202
CONTENTS v
13.3 Compliance and enforcement 202
13.4 Control and abatement technology 204
13.5 Public awareness and information 207
13.6 Public health advice and intervention
(including prevention and rescue services) 209
13.7 Operating within an integrated coastal area management framework 212
13.8 References 214
APPENDIX A. LIFEGUARDS 216
Index 220
vi GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
List of acronyms and abbreviations
vii
AFRI acute febrile respiratory illness AIDS acquired immune deficiency syndrome ASP amnesic shellfish poisoning
BCC basal cell carcinoma
CBO community-based organization
CDC Centers for Disease Control and Prevention (USA) cfu colony-forming unit
COGP Code of Good Practice CPR cardiopulmonary resuscitation DALY disability adjusted life year DSP diarrhetic shellfish poisoning EAP emergency action plan or procedure
EC European Commission
GAE granulomatous amoebic encephalitis GI gastrointestinal
HACCP hazard analysis and critical control point HAV hepatitis A virus
HEV hepatitis E virus
HIA health impact assessment HIV human immunodeficiency virus
IARC International Agency for Research on Cancer IBM integrated basin management
ICAM integrated coastal area management
ID50 dose of microorganisms required to infect 50% of individuals exposed ILS International Life Saving Federation
i.p. intraperitoneal
LOAEL lowest-observed-adverse-effect level
MM malignant melanoma
MOE Ministry of Environment MOH Ministry of Health MOT Ministry of Tourism
NGO nongovernmental organization NMSC non-melanoma skin cancer NOAEL no-observed-adverse-effect level NSP neurotoxic shellfish poisoning
PAM primary amoebic meningoencephalitis PDF probability density function
PFD personal flotation device pfu plaque-forming unit PSP paralytic shellfish poisoning QA quality assurance
QMRA quantitative microbial risk assessment SCC squamous cell carcinoma
SLRA screening-level risk assessment SOP standard operating procedure SPF sun protection factor
TCBS thiosulfate–citrate–bile salts–sucrose TDI tolerable daily intake
USLA United States Lifesaving Association
UV ultraviolet
UVR ultraviolet radiation WHO World Health Organization WTO World Tourism Organization
viii GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
Preface
ix
T
he World Health Organization (WHO) has been concerned with health aspects of the management of water resources for many years and publishes various documents concerning the safety of the water environment and its importance for health. These include a number of normative “guidelines” documents, such as the Guidelines for Drinking-water Quality and the Guidelines for Safe Use of Wastewater and Excreta in Agriculture and Aquaculture. Documents of this type are intended to provide a basis for standard setting. They represent a consensus view among experts on the risk to health represented by various media and activities and on the effec- tiveness of control measures in protecting health. They are based on critical review of the available evidence. Wherever possible and appropriate, such guidelines docu- ments also describe the principal characteristics of the monitoring and assessment of the safety of the medium under consideration as well as the principal factors affect- ing decisions to be made in developing strategies for the control of the health hazards concerned.The Guidelines for Safe Recreational Water Environments are published in two volumes:
• Volume 1: Coastal and Fresh Waters provides a review and assessment of the health hazards encountered during recreational use of coastal and freshwater environments. It includes the derivation of guideline values and explains the basis for the decision to derive or not to derive them. It addresses a wide range of types of hazard, including hazards leading to drowning and injury, water quality, exposure to heat, cold and sunlight, and dangerous aquatic organisms;
and provides background information on the different types of recreational water activity (swimming, surfing, etc.) to enable informed readers to interpret the Guidelines in light of local and regional circumstances. With regard to water quality, separate chapters address faecal pollution, free-living microorganisms, freshwater algae, marine algae and chemical aspects. It describes prevention and management options for responding to identified hazards.
• Volume 2: Swimming Pools, Spas and Similar Recreational Water Environments provides a review and assessment of the health hazards associated with recre- ational waters of this type; their monitoring and assessment; and activities avail- able for their control through education of users, good design and construction, and good operation and management. It includes the derivation of guidelines including guideline values and explains the basis for the decision to derive or
not to derive them. It addresses a wide range of types of hazard, including water quality, hazards leading to drowning and injury, contamination of associated facilities and air quality.
In addition to the above volumes of the Guidelines for Safe Recreational Water Envi- ronments, a practical guide entitled Monitoring Bathing Waters,1has been produced.
It describes the principal characteristics of and approaches to the monitoring and assessment of coastal and freshwater recreational water environments. It emphasizes the need to utilize information of diverse types and from diverse sources in order to develop a valid assessment; and the need to establish effective links between the infor- mation generated and interventions to control risk in both the short and long term.
It includes comprehensive practical guidance for the design, planning and imple- mentation of monitoring programmes and assessments; and a Code of Good Prac- tice for the monitoring and assessment of recreational water environments, to assist countries in developing such codes for national use and to promote international harmonization. Material relating to toxic cyanobacteria, including that in chapters 7 and 8 is based upon Toxic Cyanobacteria in Water,2which was prepared by an inter- national group of experts.
The development of WHO activity on ‘recreational’ or ‘bathing’ water can be traced back to two expert consultations in the 1970s.3These meetings highlighted the breadth of possible hazards associated with recreational water use and noted that prospective volunteer studies offered the “best hope of progress” in terms of estab- lishing links between water quality and bather health. They also suggested the grading of beaches according to bands of indicator counts and the use of sanitary assessments for beaches. These initial meetings were followed by a series of expert consultations.
The meeting in Valetta, Malta held during 1989, reviewed the status of microbial guidelines for bathing waters and examined the potential protocols for epidemiolog- ical investigations. The importance of protocol design was clear at the Valetta meeting, and two principal approaches were reviewed—namely, the prospective case–control and the randomized trial. Two years later in Athens, Greece the early results of epidemiological investigations that employed both protocols were reviewed.
It was decided at this meeting that both approaches were appropriate and could yield useful data for Guidelines derivation. The results of a series of major epidemiologi- cal studies in the United Kingdom were presented and critically reviewed at a meeting held in Athens, Greece in 1993.
The preparation of the Guidelines for Safe Recreational Water EnvironmentsVolume 1 covered a period of almost a decade and involved the participation of numerous institutions, more than 130 experts from 33 countries worldwide, and further review- ers and meetings. The work of the individuals concerned (see Acknowledgements) was central to the completion of the work and is much appreciated.
x GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
1 Edited by J. Bartram and G. Rees, published in 2000 by E & FN Spon on behalf of WHO.
2 Edited by I. Chorus and J. Bartram, published in 1999 by E & FN Spon on behalf of WHO
3 Meetings: Ostend, 1972; Bilthoven, 1974; Valetta 1989; Athens 1991; Athens 1993; Bad Elster 1996;
Jersey 1997; Farnham 1998; Annapolis 1999; Farnham 2001.
In 1994, following discussions between the WHO Regional Office for Europe and WHO Headquarters, it was agreed to initiate development of guidelines concerning recreational use of the water environment, examining all possible health outcomes from both natural waters and swimming pools, including those related to water quality. This was undertaken as a collaborative initiative between WHO Headquar- ters and the WHO European Centre for Environment and Health, Rome, Italy. A comprehensive review of the scientific literature on sewage pollution of recreational water and health, eventually published as Prüss (1998), provided the focus for an expert consultation in Bad Elster in 1996. This meeting concluded that the epi- demiological basis had been laid for evidence-based normative guidelines on faecal pollution of recreational water. The consultation also received information on new research findings quantifying the impacts of non-sewage sources of faecal bacteria on recreational water compliance with microbial water quality criteria. The implications of these findings were that many bathing waters might fail current water quality norms because of the influence of diffuse source pollution, which would not be reduced by sewage treatment alone.
At a further expert consultation hosted and co-sponsored by the States of Jersey in 1997 drafts of all chapters of the two volumes of Guidelines were reviewed, these were revised and further reviewed at a meeting the following year in Farnham, UK 1998. The Draft Guidelines for coastal and fresh waters were then submitted for international expert appraisal and received intensive review.
In 1999, an expert consultation co-sponsored by the US EPA and held in Annapolis, USA, resulted in the “Annapolis Protocol” (WHO, 1999), which sug- gested a new approach towards evaluation and regulation of faecal pollution of bathing waters. The Annapolis Protocol outlines a combined sanitary inspection and microbial measurement approach that is used to classify recreational waters. In addi- tion, the protocol suggests the use of relevant information to facilitate real-time public health protection. Thus, the principal focus of regulation is expanded from retro- spective numerical compliance assessment to include real-time management and public health protection. A further expert consultation to take account of the Annapolis protocol and other newly available information in the draft guidelines was held in Farnham, UK, in 2001. The Guidelines were finalized through a series of chapter-by-chapter conference calls with selected experts, in November 2002.
During the development of the Guidelines, careful consideration was given to pre- vious assessments, in particular the work of the Mediterranean Action Plan, the Black Sea Environmental Programme, the activities undertaken by and for the European Commission, the activities undertaken by the US Environmental Protection Agency, including its “BEACH” programme and others.
In light of the importance of the subject area for health and the degree of atten- tion it receives from the political and scientific communities and the general public, it is envisaged that new information will become available rapidly during future years.
WHO would be pleased to learn of major related developments and will endeavour to ensure the continuing validity of the Guidelines through issuing addenda or further editions as appropriate.
PREFACE xi
References
Prüss A (1998) A review of epidemiological studies from exposure to recreational water. Inter- national Journal of Epidemiology, 27: 1–9.
WHO (1999) Health-based monitoring of recreational waters: the feasibility of a new approach (the “Annapolis Protocol”).Geneva, World Health Organization
(http://www.who.int/water_sanitation_health/Recreational_waters/Annapolis.pdf )
(Protection of the Human Environment, Water Sanitation and Health Series, WHO/SDE/WSH.99.1).
xii GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
Acknowledgements
xiii
T
he World Health Organization wishes to express its appreciation to all those whose efforts made possible the production of the Guidelines for Safe Recreational Water Environments. Volume 1: Coastal and Fresh Waters, in particular to Jamie Bartram (Coordinator, Water Sanitation and Health at WHO Headquarters and formerly Regional Advisor for Water and Wastes, WHO European Centre for Environment and Health, Rome), who coordinated the development of the Guidelines.An international group of experts provided material and participated in the devel- opment and review of the Guidelines for Safe Recreational Water Environments. Volume 1: Coastal and Fresh Waters. Many individuals contributed to each chapter, directly and through associated activities. The contributions of the following to the develop- ment of these Guidelines is appreciated:
Houssaïn Abouzaïd, WHO Regional Office for Eastern Mediterranean, Cairo, Egypt Ben Aissa, Institut Pasteur de Tunis, Tunis, Tunisia
Lisa Almodovar, US Environmental Protection Agency, Washington DC, USA Julian Andelman, University of Pittsburgh, Pittsburgh, USA
Nicholas Ashbolt, Co-operative Research Centre for Water Quality and Treatment, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales, Australia
Sandra Azevedo, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil Linda Bagge, Environmental Protection Agency, Copenhagen, Denmark
Jamie Bartram, WHO, Geneva, Switzerland (formerly of WHO European Centre for Environment and Health, Rome, Italy)
Simona Battucci, Procter & Gamble, Rome, Italy
Joost Bierens, VU University Medical Centre, Amsterdam, The Netherlands Lucia Bonadonna, Istituto Superiore di Sanità, Rome, Italy
Juan Borrego, University of Malaga, Malaga, Spain Robert Bos, WHO, Geneva, Switzerland
Lee Bowling, Department of Land and Water Conservation, Paramatta, New South Wales, Australia
B. Chris Brewster, International Life Saving Federation, San Diego, CA, USA Raymond Briggs, Robens Centre for Public and Environmental Health, Guildford,
Surrey, UK
Igor Brown, Cyanobacteria Biology Research Laboratory, Odessa State University, Odessa, Ukraine
Milena Bruno, Istituto Superiore di Sanità, Rome, Italy
Christine Bullock-Ramsumair, Institute of Marine Affairs, Trinidad
Michael Burch, Cooperative Research Centre for Water Quality and Treatment, Salisbury, Australia
Sarah Butcher, (formerly of Centre for Ecology and Hydrology Oxford, Oxford, UK)
Rebecca Calderon, US Environmental Protection Agency, Cincinnati, OH, USA Rudy Calders, Provinciaal Instituut voor Hygienne, Antwerpen, Belgium Wayne Carmichael, Wright State University, Dayton, OH, USA
Natale Cascinelli, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy Maurizio Cavalieri, Local Agency for Electricity and Water Supply, Rome, Italy J.P. Cesarini, Research Laboratory for Skin Cancer, Paris, France
Ingrid Chorus, Institute for Water, Soil and Air Hygiene, Federal Environmental Agency, Berlin, Germany
Geoff Codd, Department of Biological Sciences, University of Dundee, Dundee, UK P. Cornelius, The Natural History Museum, London, UK
Joseph Cotruvo, NSF International, Washington DC, USA
David Cunliffe, Public and Environmental Health Services, Department of Human Services, South Australian Health Commission, Adelaide, Australia
Anders Dalsgaard, Department of Veterinary Microbiology, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark
John de Louvois, retired (formerly of Public Health Laboratory Service Communi- cable Disease Surveillance Centre, London, UK)
Mary Drikas, Australian Water Quality Centre, Adelaide, Australia Karin Dubsky, Trinity College, Dublin, Ireland
Alfred P. Dufour, National Exposure Research Laboratory, US Environmental Pro- tection Agency, Cincinnati, OH, USA
Henrik Enevoldsen, UNESCO/Intergovernmental Oceanographic Commission, Science and Communication Centre for Harmful Algae, University of Copen- hagen, Copenhagen, Denmark
Ian Falconer, University of Adelaide, Adelaide, Australia
Jutta Fastner, Institute for Water, Soil and Air Hygiene, Federal Environment Agency, Berlin, Germany
John Fawell, independent consultant, Flackwell Heath, UK (formerly of WRc, Medmenham, UK)
Peter Fenner, School of Medicine, James Cook University, Queensland, Australia Lorna Fewtrell, Centre for Research into Environment and Health, Crewe, Cheshire,
UK
Maria Jose Figueras, University Rovira and Virgili, Tarragona-Reus, Spain Jim Fitzgerald, South Australian Health Commission, Adelaide, Australia Jay Fleisher, SUNY Health Science Center at Brooklyn, Brooklyn, NY, USA Walter Frick, US Environmental Protection Agency, Cincinnati, OH, USA Enzo Funari, Istituto Superiore di Sanità, Rome, Italy
xiv GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
Robert Gearheart, Department of Environmental Resources, Humboldt State Uni- versity, Arcata, CA, USA
Frank Golden, University of Portsmouth, Portsmouth, UK
Ernest Gould, Centre for Ecology and Hydrology Oxford, Oxford, UK
Sylvie Goyet, independent consultant, Paris, France (formerly of World Wide Fund for Nature, Gland, Switzerland)
Willie Grabow, University of Pretoria, Pretoria, South Africa
Ross Gregory, (formerly Water Research Centre, Swindon, Wiltshire, UK) Brian Guthrie, Pool Water Treatment Advisory Group, Norfolk, UK Gustaaf M. Hallegraeff, University of Tasmania, Hobart, Tasmania, Australia Ken-Ichi Harada, Meijo University, Nagoya, Japan
Philippe Hartemann, Nancy, France
Rudy Hartskeerl, Royal Tropical Institute (KIT), Amsterdam, The Netherlands Arie Havelaar, National Institute of Public Health and the Environment (RIVM),
Bilthoven, The Netherlands
Nancy Hearne, (formerly of NSF International, Washington, DC, USA) Rick Hoffmann, US Environmental Protection Agency, Washington, DC
Christiane Höller, Institute for Hygiene and Environmental Medicine, Kiel, Germany
Steve Hrudey, University of Alberta, Edmonton, Alberta, Canada
Paul Hunter, University of East Anglia, Norwich, UK (formerly of Public Health Laboratory Service)
Adnan Hyder, John Hopkins University, Baltimore, USA
Alan Jenkins, Institute of Hydrology, Centre for Ecology and Hydrology, Walling- ford, Oxon, UK
Gary Jones, Commonwealth Scientific and Industrial Research Organization (Land and Water), Brisbane, Australia
Huw Jones, Welsh Office, Cardiff, UK (formerly of Department of the Environment, Transport and the Regions, London, UK)
Mihaly Kadar, National Institute of Hygiene, Budapest, Hungary George Kamizoulis, WHO, Athens, Greece
David Kay, Centre for Research into Environment and Health, University of Wales, Aberystwyth, Ceredigion, Wales (formerly of University of Leeds, Leeds, UK)
Simon Kilvington, Department of Microbiology and Immunology, University of Leicester, Leicester, UK
Olive Kobusingye, Injury Control Center, Makerere University, Kampala, Uganda Fumio Kondo, Aichi Prefectural Institute of Public Health, Nagoya, Japan Michael Kramer, Rheinische Friedrich-Wilhelms Universität, Bonn, Germany Tine Kuiper-Goodman, Health Canada, Ottawa, Ontario, Canada
Inna Kuzanova, Sanitary and Hygiene Scientific Research Institute, Tbilisi, Georgia Bob Lacey, Water Research Centre, Medmenham, UK
Linda Lawton, Robert Gordon University of Aberdeen, Aberdeen, UK
ACKNOWLEDGEMENTS xv
Lucianne Licari, Environmental Health, Department of Health Policy and Planning, Malta
Juan Lopez-Pila, Institut für Wasser Boden und Lufthygiene, Berlin, Germany Richard Lugg, Environmental Health Consultant, Leederville, Western Australia Patricia Madden, The Scottish Office, Department of Health, Edinburgh, UK Mariagloria Marinari, Ufficio di Igiene Publica, Livorno, Italy
Blahoslav Marsalek, Institute of Botany, Brno, Czech Republic Athena Mavridou, National School of Public Health, Athens, Greece
Graham McBride, National Institute of Water and Atmospheric Research Ltd., Hamilton, New Zealand
Elizabeth McDonnell, Water Quality Division, Department of Environment, Food and Rural Affairs (formerly Department of the Environment, Transport and the Regions), London, UK
Charles McGee, Orange County Sanitation District, Fountain Valley, CA, USA Melissa Melvin, US Environmental Protection Agency, Washington, DC
Bettina Menne, WHO European Centre for Environment and Health, Rome, Italy Jane Metcalfe, Centre for Ecology and Hydrology, Swindon, UK
Art Mittelstaedt, Recreational Safety Institute, New York, NY, USA Eric Mood, School of Medicine, Yale University, New Haven, CT, USA
Helene Munk-Sorensen, Department of Marine and Coastal Areas, Hojbjerg, Denmark
Luuc Mur, University of Amsterdam, Amsterdam, Netherlands Michele Muscillo, Istituto Superiore di Sanità, Rome, Italy
Judit Padisák, Institute of Biology, University of Veszprém, Veszprém, Hungary Ierotheos Papadopolous, European Commission, Athens, Greece (formerly Water
Unit, European Commission, Brussels, Belgium)
Latisha Parker, US Environmental Protection Agency, Cincinnati, OH, USA Walter Pasini, Tourist Health Centre, Rimini, Italy
Margie Peden, WHO, Geneva, Switzerland
Robin Philipp, United Bristol Healthcare Trust, Bristol, Avon, UK
Edmund Pike, Consultant Microbiologist, Reading, Berkshire, UK (formerly of WRc, Medmenham, UK)
Alain Pinter, deceased (formerly National Institute of Hygiene, Budapest, Hungary) Kathy Pond, Robens Centre for Public and Environmental Health, University of
Surrey, Guildford, Surrey, UK (formerly of WHO, Rome, Italy) Annette Prüss, WHO, Geneva, Switzerland
Gareth Rees, Askham Bryan College, York, UK (formerly of Robens Centre for Public and Environmental Health, University of Surrey, UK)
Eva Rehfuess, WHO, Geneva, Switzerland
Colin Reynolds, Centre for Ecology and Hydrology (formerly the Institute of Fresh- water Ecology), Windermere, UK
John Ridgway, Water Research Centre, Medmenham, UK Will Robertson, Health Canada, Ottawa, Ontario, Canada
Wim Rogmans, Consumer Safety Institute, Amsterdam, Netherlands
xvi GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
David Rosenblatt, State of New Jersey Department of Environmental Protection, Trenton, NJ, USA
Philip Rushbrook, France (formerly WHO European Centre for Environment and Health, Nancy, France)
Ronnie Russell, Trinity College, Dublin, Ireland
Henry Salas, Pan American Health Organization/WHO, Washington DC, USA (formerly of Pan American Center for Sanitary Engineering and Environmental Sciences, Lima, Peru)
Stephen Schaub, US Environmental Protection Agency, Washington DC, USA Katrin Scheiner-Bobis, (formerly Institute for Water, Soil and Air Hygiene, Federal
Environmental Agency, Berlin, Germany) Germany Peter Scott, Melbourne Water, Melbourne, Australia Kaarina Sivonen, University of Helsinki, Helsinki, Finland
Christopher Sharp, National Radiological Protection Board, Didcot, UK Yu Shun-Zhang, Institute of Public Health, Shanghai, China
Joth Singh, Caribbean Environment & Health Institute, Castries, St. Lucia Olav Skulberg, Norwegian Institute for Water Research, Oslo, Norway Jeffrey Soller, Eisenberg, Oliverieri & Associates, Oakland, CA, USA
Ann Storey, Robens Centre for Public and Environmental Health, Guildford, Surrey, UK
Ernst Stottmeister, Institut für Wasser Boden und Lufthygiene, Bad Elster, Germany Robert Tanner, NSF International, Brussels, Belgium
Desmond Till, Consultant Public Health Microbiologist, Wellington, New Zealand Maggie Tomlinson, Department of Health, London, UK
Hans Utkilen, National Institute for Public Health, Oslo, Norway Bert van Maele, European Commission, Brussels, Belgium
Jessica Vapnek, Food and Agriculture Organization of the United Nations, Rome, Italy
Carolyn Vickers, WHO, Geneva, Switzerland
Timothy Wade, University of California, Berkley, CA, USA Rowena White, St. Helier, Jersey, Channel Islands
Claudia Wiedner, University of Amsterdam, Amsterdam, The Netherlands
William B. Wilkinson, retired (formerly of Centre for Ecology and Hydrology, Wallingford, Oxon, UK)
Allan T. Williams, Bath Spa University College, Newton Park, Bath, Avon, UK Adam Wooler, Royal National Lifeboat Institution, Saltash, Cornwall, UK (formerly
of the Surf Life-Saving Association of Great Britain, Plymouth, Devon, UK) Thanks are also due to Marla Sheffer for editing the complete text of the Guidelines, and Lorna Fewtrell for overseeing the review process and finalization of the document.
The preparation of these Guidelines would not have been possible without the generous support of the following, which is gratefully acknowledged: the European Commission; the States of Jersey, United Kingdom; the Department of the
ACKNOWLEDGEMENTS xvii
Environment, Transport and the Regions of the United Kingdom; the Ministry of Health of Germany; the Ministry of Environment of Germany; the Ministry of Health of Italy; the Swedish International Development Cooperation Agency, Sweden and the United States Environmental Protection Agency.
xviii GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
Executive summary
xix
T
his volume of the Guidelines for Safe Recreational Water Environments describes the present state of knowledge regarding the impact of recreational use of coastal and freshwater environments upon the health of users—specifically drowning and injury, exposure to cold, heat and sunlight, water quality (especially exposure to water contaminated by sewage, but also exposure to free-living pathogenic microorganisms in recreational water), contamination of beach sand, exposure to algae and their prod- ucts, exposure to chemical and physical agents, and dangerous aquatic organisms. As well, control and monitoring of the hazards associated with these environments are discussed.The primary aim of the Guidelines is the protection of public health. The purpose of the Guidelines is not to deter the use of recreational water environments but instead to ensure that they are operated as safely as possible in order that the largest possible population gets the maximum possible benefit. The adverse impacts of recre- ational use of coastal and freshwater environments upon the health of users must be weighed against the enormous benefits to health and well-being—rest, relaxation and exercise—associated with the use of these environments.
The Guidelines are intended to be used as the basis for the development of inter- national and national approaches (including standards and regulations) to control- ling the health risks from hazards that may be encountered in recreational water environments, as well as providing a framework for local decision-making. The Guidelines may also be used as reference material for industries and operators prepar- ing development projects in recreational water areas, as a checklist for understand- ing and assessing potential health impacts of recreational projects, and in the conduct of environmental impact and environmental health impact assessments in particular.
The information provided is generally applicable to any coastal or freshwater area where recreational water use occurs. The preferred approaches adopted by national or local authorities towards implementation of the Guidelines, including guideline values, may vary depending on social, cultural, environmental and economic characteristics, as well as knowledge of routes of exposure, the nature and severity of hazards, and the effectiveness of control measures.
A guideline can be:
• a level of management;
• a concentration of a constituent that does not represent a significant risk to the health of members of significant user groups;
• a condition under which such exposures are unlikely to occur; or
• a combination of the last two.
When a guideline is not achieved, this should be a signal to investigate the cause of the failure and identify the likelihood of future failure, to liaise with the author- ity responsible for public health to determine whether immediate action should be taken to reduce exposure to the hazard, and to determine whether measures should be put in place to prevent or reduce exposure under similar conditions in the future.
Drowning and injury prevention
Drowning, which has been defined as death arising from impairment of respiratory function as a result of immersion in liquid, is a major cause of death worldwide, par- ticularly for male children. Near drowning is also a serious problem as it may have life-long effects. The recovery rate from near drowning may be lower among young children than among teenagers and adults. Studies show that the prognosis for sur- vival depends more on the effectiveness of the initial rescue and resuscitation than on the quality of subsequent hospital care.
Drowning may be associated with swimming as well as with recreational water uses involving minimal water contact, such as recreational use of watercraft (yachts, boats, canoes) and fishing. Alcohol consumption is one of the most frequently reported contributory factors associated with drownings for adults, whereas lapses in parental supervision are most frequently cited for children. In cold weather, immer- sion cooling may be a significant contributory factor.
Of sports-related spinal cord injuries, the majority appear to be associated with diving. Injuries in diving incidents are almost exclusively located in the cervical ver- tebrae, resulting in quadriplegia or paraplegia. Data suggest that body surfing and striking the bottom is the most common cause of spinal injury. Alcohol consump- tion may contribute significantly to the frequency of injury. Other injuries associated with recreational water use activities include brain and head injuries, fractures, dis- locations and other minor impact injuries, and cuts, lesions and punctures.
Prevention is the best way to reduce the incidence of injury and death related to the aquatic environment, and the majority of injuries can be prevented by appro- priate measures at a local level. Physical hazards should first be removed or reduced if possible, or measures should be taken to prevent or reduce human exposure. Phys- ical hazards that cannot be completely dealt with in this way should be the subject of additional preventive or remedial measures. These include drowning prevention programmes, public information and warnings (such as signs, flags and general edu- cation and awareness raising), the provision of effective lifeguard supervision and rescue services, and the establishment of different recreation zones for different recreational activities using lines, buoys and markers.
Monitoring of a site for existing and new hazards should be undertaken on a regular basis. The frequency and timing of inspections will vary with the location.
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Sun, heat and cold
The recreational use of water environments sometimes leads to exposure of indi- viduals to extreme solar radiation and to extreme conditions of heat or cold.
Ultraviolet radiation (UVR) from sunlight can be divided into three bands: UVA, UVB and UVC. As the ozone layer becomes depleted, the protective filter provided by the atmosphere is progressively reduced, and human beings are exposed to higher UV levels, in particular higher UVB levels.
Overexposure to UVR may result in acute and chronic damage to the skin, the eyes and the immune system. The most noticeable acute effect of excessive UV expo- sure is erythema, the familiar inflammation of the skin commonly termed sunburn.
Photokeratitis and photoconjunctivitis are other acute effects of UV exposure.
Chronic effects include two major public health problems: skin cancers (both non- melanoma skin cancers and malignant melanoma) and cataracts. Chronic exposure to UVR also causes a number of degenerative changes in the skin (e.g., freckles) and accelerates skin aging. There is also increasing evidence for an immunosuppressive effect of both acute high-dose and chronic low-dose UV exposure on the human immune system.
Not all effects of UV radiation are adverse. The best known beneficial effect is the stimulation of the production of vitamin D in the skin. UVR from artificial sources is also used to treat several diseases and dermatological conditions, including rickets, psoriasis, eczema and jaundice.
Simple protective measures are available and should be adopted to avoid adverse health effects on the skin, eyes and immune system. These include minimizing the amount of time spent in the sun, including complete avoidance of midday sun expo- sure; seeking shade; and wearing loose-fitting and tightly woven clothing, a broad- brimmed hat and wrap-around sunglasses. Furthermore, a broad-spectrum sunscreen with sun protection factor of 15 or more should be applied liberally on all areas of the body not covered by clothing and should be reapplied often. Sun protection pro- grammes to raise awareness and achieve changes in lifestyle are urgently needed to slow down and eventually reverse the trend towards more skin cancers. The global solar UV index is an important vehicle to raise public awareness of UVR and the risks of excessive UV exposure and to alert people to the need to adopt protective measures.
Exposure to cold water may cause considerable problems for users of recreational waters. The immediate effect of sudden immersion in cold water can be a debilitat- ing reflex response called cold shock, which includes life-threatening respiratory and cardiovascular effects and may lead to drowning. Sudden immersion in cold water often results in impaired swimming ability, which is believed to be responsible for the majority of sudden cold-water immersion deaths. Safety precautions include wearing suitable protective garments when swimming in cold water and using a life- jacket when boating to keep airways clear of water even when unconscious.
In a hot environment, people can suffer serious physical ailments, such as heat cramps, heat exhaustion and heat stroke. The very young, the elderly, patients using
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drugs that interfere with temperature regulation, people suffering from pre-existing chronic diseases and frequent consumers of alcohol appear to be particularly suscep- tible. Avoidance measures include consumption of non-alcoholic, non-caffeinated beverages, replacement of salt lost through sweating and retreat to shaded areas. Dis- orders due to heat occur most frequently when there are rapid changes in thermal conditions, such as during heat waves.
Faecal pollution and water quality
The most frequent adverse health outcome associated with exposure to faecally con- taminated recreational water is enteric illness. A cause–effect relationship between faecal or bather-derived pollution and acute febrile respiratory illness (AFRI), which is a more severe health outcome than gastroenteritis, has also been shown.
There is consistency in the overall body of evidence concerning health effects from faecally polluted recreational waters, and a series of randomized controlled trials per- formed in the United Kingdom form the key studies for derivation of guideline values for the microbiological quality of recreational waters. For marine waters, only intes- tinal enterococci (faecal streptococci) showed a dose–response relationship for both gastrointestinal illness and AFRI. The guideline values are expressed in terms of the 95th percentile of numbers of intestinal enterococci per 100 ml and represent readily understood levels of risk based on the exposure conditions of the key studies.
There is inadequate evidence with which to directly derive a water quality guide- line value for fresh water. Application of the guideline values derived for seawaters to fresh waters would be likely to result in a lower illness rate in freshwater swim- mers, providing a conservative guideline in the absence of suitable epidemiological data for fresh waters. Studies under way may provide a more adequate basis on which to develop freshwater guideline values.
The guideline values should be interpreted or modified in light of regional and/or local factors. Such factors include the nature and seriousness of local endemic illness, population behaviour, exposure patterns, and sociocultural, economic, environ- mental and technical aspects, as well as competing health risk from other diseases that are not associated with recreational water.
The initial classification of a recreational water environment is based upon the combination of evidence for the degree of influence of (human) faecal material (by sanitary inspection of beach and water catchment) alongside counts of suitable faecal index bacteria (a microbial quality assessment). Information to be collected during sanitary inspections should cover at least the three most important sources of human faecal contamination of recreational water environments for public health purposes:
sewage; riverine discharges (where the river is a receiving water for sewage discharges and either is used directly for recreation or discharges near a coastal or lake area used for recreation); and bather contamination, including excreta. Where human inputs are minimal, investigation of animal faecal inputs should be explored.
In the microbial water quality assessment, the sampling programme should be rep- resentative of the range of conditions in the recreational water environment while it is being used. An important issue is that of collecting sufficient numbers of samples
xxii GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
so as to make an appropriate estimation of the likely densities to which recreational water users are exposed. The precision of the estimate of the 95thpercentile is higher when sample numbers are increased. The number of results available can be increased significantly by pooling data from multiple years, unless there is reason to believe that local (pollution) conditions have changed. For practical purposes, data on at least 100 samples from a 5-year period and a rolling 5-year data set can be used for micro- bial water quality assessment purposes.
The outputs from the sanitary inspection and the microbial water quality assess- ment can be combined to give a five-level classification for recreational water envi- ronments—very good, good, fair, poor and very poor. Following initial classification, it is proposed that all categories of recreational water environment would be subject to an annual sanitary inspection (to determine whether pollution sources have changed) and continued water quality monitoring.
Another component of the assessment of a recreational water environment is the possible “upgrading” of a recreational water environment if a significant change in management reduces human exposure to microbial risk.
Follow-up analyses are recommended when the intestinal enterococci counts are high but the sanitary inspection suggests low sanitary impact, or vice versa. A primary role of the follow-up is to help identify the source of the faecal pollution, thereby assisting in the assessment and management of faecal contamination in recreational water environments.
In certain circumstances, there may be a risk of transmission of pathogens associ- ated with more severe health effects (such as infectious hepatitis or typhoid fever) through recreational water use. Public health authorities should be alert to such hazards where exposure may occur and should take appropriate action to protect public health.
Population groups that may be at higher risk of disease include the young, the elderly and the immunocompromised, as well as visiting populations susceptible to locally endemic disease. If such groups are significant water users, then this should be taken into account in risk assessment and management.
Management action in response to a recreational water environment classification indicating unacceptable faecal contamination can be both immediate, such as public health advisories, and long term, such as pollution abatement.
Free-living microorganisms
In addition to microorganisms introduced to recreational waters through human or animal faecal contamination, a number of pathogenic microorganisms are free-living in such areas or, once introduced, are capable of colonizing the environment.
Vibriospecies are natural inhabitants of marine aquatic environments in both tem- perate and tropical regions. The occurrence of vibrios does not correlate with the occurrence of the traditionally used bacterial faecal index organisms, except perhaps in waters receiving human wastes from disease outbreaks (mainly cholera). Due to the ubiquitous nature of Vibriospecies in the aquatic environment, their presence in bathing water cannot be controlled by water quality control measures such as waste-
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water treatment and disinfection. Human carriers and shedding appear to be of only limited importance in the epidemiology of Vibrioinfections associated with recre- ational water use. For V. cholerae, 106organisms or more are typically needed to cause cholera, so that it is unlikely that persons bathing or involved in other recreational water activities would ingest vibrios in numbers high enough to cause gastrointes- tinal disease. However, the risk of extraintestinal infections associated with human pathogenic Vibrio species, especially wound and ear infections, during recreational activities in water is of health importance, although the infectious doses for such infections are unknown.
Aeromonas spp. are considered autochthonous inhabitants of aquatic environments and are ubiquitous in surface fresh and marine waters, with high numbers occurring during the warmer months of the year. Clinical isolation of these microbes presents the same seasonal distribution. Numbers may be high in both polluted and unpol- luted habitats with densities ranging from <1 to 1000 cells per ml. Sewage can also contain elevated numbers (106–108cells per ml) of aeromonads. Aeromonashas been found to have a role in a number of human illnesses including gastroenteritis. Cases of wound infections in healthy people associated with recreational water have been described, as have cases of pneumonia following aspiration of contaminated recreational water.
Free-living amoebae are unicellular protozoa common to most soil and aquatic environments. Of the many hundreds of species of free-living amoebae, only members of the genus Acanthamoeba, Naegleria fowleriand Balamuthia mandrillaris are known to infect humans, often with fatal consequences. Acanthamoeba have been isolated from natural and artificial waters. Certain species are pathogenic to humans and cause two clinically distinct diseases affecting the central nervous system: gran- ulomatous amoebic encephalitis (GAE) and inflammation of the cornea (keratitis).
Naegleria fowleri, which is found in thermal freshwater habitats worldwide, causes primary amoebic meningoencephalitis (PAM) in humans. PAM is usually fatal, with death occurring in 3–10 days after exposure. Infection usually results from swim- ming in contaminated water, although the infectious dose for humans is not known.
B. mandrillarisencephalitis is largely a disease of the immunocompromised host, and certain cases of GAE attributed to Acanthamoebahave in fact been shown to have been caused by B. mandrillaris.
Leptospires are excreted in the urine of infected animals, which can then con- taminate soil, mud, groundwater, streams and rivers. Humans become infected either directly through contact with infected urine or indirectly via contaminated fresh water or soil. Virulent leptospires gain entry to the body through cuts and abrasions of the skin and through the mucosal surfaces of the mouth, nose and conjunctiva.
In cases due to exposure to recreational water, the incubation period seems to vary between 2 and 30 days, but generally is between 7 and 14 days. The clinical mani- festations of leptospirosis vary considerably in form and intensity, ranging from a mild flu-like illness to a severe and potentially fatal form of the disease, characterized by liver and kidney failure.
xxiv GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
Evidence suggests that although infection with free-living microorganisms or path- ogenic leptospires via recreational water use may be life-threatening, the incidence of such infection is very low and, in many cases, is limited to specific areas. As such, no specific guideline values have been recommended, although authorities should be aware of the potential hazards posed by these organisms and act accordingly. Assess- ment of the likely hazard (e.g., the likelihood of thermal warming of fresh waters) and education of water users and health professionals are important control measures.
Microbial aspects of beach sand quality
Bacteria, fungi, parasites and viruses have all been isolated from beach sand. A number of them are potential pathogens. Factors promoting the survival and dis- persion of pathogens include the nature of the beach, tidal phenomena, the presence of sewage outlets, the season, the presence of animals and the number of swimmers.
Transmission may occur through direct person-to-person contact or by other means, although no route of transmission has been positively demonstrated.
Concern has been expressed that beach sand or similar materials may act as reser- voirs or vectors of infection. However, the capacity of microorganisms that have been isolated from beach sand to infect bathers and beach users remains undemonstrated, and the real extent of their threat to public health is unknown. There is therefore no evidence to support establishment of a guideline value for index organisms or path- ogenic microorganisms on beach sand.
The principal microbial risk to human health encountered upon beaches and similar areas is that arising from contact with animal excreta, particularly from dogs.
Regulations that restrict access seasonally on frequently used beaches or place an obli- gation upon the owner to remove animal excreta, increased public awareness and beach cleaning are preventive management actions.
Algae and cyanobacteria in coastal and estuarine waters
Several human diseases have been reported in association with many toxic species of dinoflagellates, diatoms, nanoflagellates and cyanobacteria (blue-green algae) that occur in the marine environment. The toxicity of these algae to humans is due to the presence of algal toxins. Marine algal toxins become a problem primarily because they concentrate in shellfish and fish that are subsequently eaten by humans, causing shellfish poisoning (not dealt with in this volume).
Marine cyanobacterial dermatitis (“swimmers’ itch” or “seaweed dermatitis”) is a severe contact dermatitis that may occur after swimming in seas containing blooms of certain species of marine cyanobacteria. The symptoms are itching and burning within a few minutes to a few hours after swimming in the sea where the cyanobacteria are suspended. Some toxic components, such as aplysiatoxin, debro- moaplysiatoxin and lyngbyatoxin A, have been isolated from marine cyanobacteria.
These toxins are highly inflammatory and are potent skin tumour promoting compounds.
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Nodularia spumigena was the first cyanobacterium recognized to cause animal death. The toxin produced by N. spumigena, called nodularin, acts as a hepatotoxin, in that it induces massive haemorrhages in the liver of mammals and causes disrup- tion of the liver structure. To date, there have been no reports of human poisoning by N. spumigena, but humans may be as susceptible to the toxins as other mammals.
Therefore, it is possible that small children may accidentally ingest toxic material in an amount that may have serious consequences.
Inhalation of a sea spray aerosol containing fragments of marine dinoflagellate cells and/or toxins (brevetoxins) released into the surf by lysed algae can be harmful to humans. The signs and symptoms are severe irritation of conjunctivae and mucous membranes (particularly of the nose) followed by persistent coughing and sneezing and tingling of the lips.
Available data indicate that the risk for human health associated with the occur- rence of marine toxic algae or cyanobacteria during recreational activities is limited to a few species and geographical areas. As a result, it is inappropriate to recommend specific guideline values.
Within areas subject to the occurrence of marine toxic algae or cyanobacteria, it is important to carry out adequate monitoring activities and surveillance pro- grammes. In affected areas, it is appropriate to provide health information to general practitioners and the general public, in particular recreational water users. Precau- tionary measures include avoiding areas with visible algal concentrations and/or algal scums in the sea as well as on the shore, avoiding sitting downwind of any algal mate- rial drying on the shore and showering to remove any algal material.
Algae and cyanobacteria in fresh water
Many species of freshwater algae may proliferate quite intensively in eutrophic (i.e., nutrient-rich) waters. However, they do not form dense surface scums or “blooms,”
as do some cyanobacteria. Toxins they may contain therefore are not accumulated to potentially hazardous concentrations. For this reason, most adverse health impacts from recreational use of fresh waters have been associated with cyanobacteria rather than with freshwater algae.
Progress in analytical chemistry has enabled the isolation and structural identifi- cation from toxic cyanobacteria of three neurotoxins (anatoxin-a, anatoxin-a(s) and saxitoxins), one general cytotoxin, which inhibits protein synthesis (cylindrosper- mopsin), and a group of toxins termed microcystins (or nodularins, found in brack- ish waters), which inhibit protein phosphatases. Most of them have been found in a wide array of genera, and some species contain more than one toxin.
Allergic or irritative dermal reactions of varying severity have been reported from a number of freshwater cyanobacterial genera (Anabaena,Aphanizomenon,Nodularia, Oscillatoria,Gloeotrichia) after recreational exposure. Bathing suits and particularly wet suits tend to aggravate such effects by accumulating cyanobacterial material and enhancing disruption of cells and liberation of cell content. It is probable that these symptoms are not due to recognized cyanotoxins but rather to currently largely unidentified substances.
xxvi GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
In contrast to dermal contact, uptake of cyanobacteria though ingestion or aspiration involves a risk of intoxication by cyanotoxins. Most documented cases of human injury through cyanotoxins involved exposure through drinking-water, and they demonstrate that humans have become ill—in some cases seriously—
through ingestion or aspiration of toxic cyanobacteria. Symptoms reported include abdominal pain, nausea, vomiting, diarrhoea, sore throat, dry cough, headache, blistering of the mouth, atypical pneumonia and elevated liver enzymes in the serum, as well as hay fever symptoms, dizziness, fatigue, and skin and eye irritations.
Health impairments from cyanobacteria in recreational waters must be differenti- ated between the chiefly irritative symptoms caused by unknown cyanobacterial sub- stances and the potentially more severe hazard of exposure to high concentrations of known cyanotoxins, particularly microcystins. A single guideline value therefore is not appropriate. Rather, a series of guideline values associated with incremental sever- ity and probability of health effects is defined at three levels.
For protection from health outcomes not due to cyanotoxin toxicity, but rather to the irritative or allergenic effects of other cyanobacterial compounds, a guideline level of 20 000 cyanobacterial cells/ml (corresponding to 10mg chlorophyll-a/litre under conditions of cyanobacterial dominance) can be derived. A level of 100 000 cyanobacterial cells/ml (equivalent to approximately 50mg chlorophyll-a/litre if cyanobacteria dominate) represents a guideline value for a moderate health alert in recreational waters. The presence of cyanobacterial scum in swimming areas repre- sents the highest risk of adverse health effects, due to abundant evidence for poten- tially severe health outcomes associated with these scums.
Because adequate surveillance is difficult and few immediate management options are available (other than precluding or discouraging use or cancelling water sports activities such as competitions), provision of adequate public information is a key short-term measure. Medium- to long-term measures are identification of the sources of nutrient (in many ecosystems phosphorus, sometimes nitrogen) pollution and sig- nificant reduction of nutrient input in order to effectively reduce proliferation not only of cyanobacteria, but of potentially harmful algae as well.
Aesthetic issues
The aesthetic value of recreational waters implies freedom from visible materials that will settle to form objectionable deposits, floating debris, oil, scum and other matter, substances producing objectionable colour, odour, taste or turbidity, and substances and conditions that produce undesirable aquatic life. Clean beaches are one of the prime parameters that are desired by recreational users. Local economies may depend on the aesthetic quality of recreational water areas, and the environmental degrada- tion of beaches is known to lead to loss of income from tourism.
Water at swimming areas should ideally be clear enough for users to estimate depth, to see subsurface hazards easily and to detect the submerged bodies of swim- mers or divers who may be in difficulty. Aside from the safety factor, clear water fosters enjoyment of the aquatic environment. The principal factors affecting the
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depth of light penetration in natural waters include suspended microscopic plants and animals, suspended mineral particles, stains that impart a colour, detergent foams and dense mats of floating and suspended debris.
Visitor enjoyment of any beach is generally marred by litter. The variety of litter found in recreational water or washed up on the beach is considerable and includes, for example, discarded food/wrapping, bottles/cans, cigarette butts, dead fish, dis- carded condoms, discarded sanitary towels, and syringes, needles and other medical wastes. Unlike most litter, medical waste and broken glass also represent hazards to health.
Objectionable smells associated with untreated sewage effluent, decaying organic matter such as vegetation, dead animals or fish, and discharged diesel oil or petrol can deter recreational water and bathing beach users. Odour thresholds and their association with the concentrations of different pollutants of the recreational water environment have not, however, been determined.
Marine debris monitoring can be used to provide information on the types, quan- tities and distribution of marine debris, to identify sources of marine debris, to explore public health issues relating to marine debris and to increase public aware- ness of the condition of the coastline. Management options include manual or mechanical beach cleaning.
Chemical and physical agents
Chemical contaminants can enter surface waters or be deposited on beaches from both natural and anthropogenic sources. Exposure is one of the key issues in deter- mining the risk of toxic effects from chemicals in recreational waters. The form of recreational activity will therefore play a significant role. Routes of exposure will be direct surface contact, including skin, eyes and mucous membranes, inhalation and ingestion. In assessing the risk from a particular contaminant, the frequency, extent and likelihood of exposure are crucial parts of the evaluation.
pH has a direct impact on the recreational uses of water only at very low or very high pH values. Under these circumstances, it may contribute to irritation of the skin and eyes.
The potential risks from chemical contamination of coastal and freshwater recre- ational waters, apart from toxins produced by marine and freshwater cyanobacteria and algae, marine animals or other exceptional circumstances, will be very much smaller than the potential risks from microbial contaminants. It is extremely unlikely that water users will come into contact with sufficiently high concentrations of most contaminants to cause ill effects following a single exposure. Even repeated (chronic) exposure is unlikely to result in ill effects at the concentrations of contaminants found in water and with the exposure patterns of recreational users. However, it remains important to ensure that chemical hazards and any potential human health risks asso- ciated with them are controlled and that users can be reassured as to their personal safety.
In most cases, the concentration of chemical contaminants will be below drink- ing-water guidelines. As long as care is taken in their application, the WHO Guide-
xxviii GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS
lines for Drinking-water Qualitycan provide a starting point for deriving values that could be used to make a preliminary risk assessment under specific circumstances.
These guideline values relate, in most cases, to lifetime exposure following con- sumption of 2 litres of drinking-water per day. For recreational water contact, an intake of 200 ml per day—100 ml per recreational session with two sessions per day—
may often be reasonably assumed.
An assessment of the chemical hazards in recreational water may involve inspect- ing the immediate area to determine if there are any immediate sources of chemical contamination, such as outfalls; considering the pattern and type of recreational use of the water to determine whether there will be extensive contact with the water and/or a significant risk of ingestion; and chemically analysing the water to support a quantitative risk assessment.
It is important that the basis of any guidelines or standards that are considered to be necessary for chemical constituents of recreational waters be made clear. Without this, there is a danger that even occasional, trivial exceedances of guidelines could unnecessarily undermine users’ confidence. It is also important in evaluating chem- ical hazards that the risks are not overestimated. The risks should be related to risks from other hazards such as drowning or microbial contamination, which will almost invariably be much greater.
Dangerous aquatic organisms
Dangerous aquatic organisms may be encountered during recreational use of fresh- water and coastal recreational environments. Such organisms vary widely and are gen- erally of local or regional importance. The likelihood and nature of human exposure often depend significantly on the type of recreational activity concerned.
Two types of risks can be distinguished in relation to dangerous aquatic species:
injury or intoxication resulting from direct encounters with predators or venomous species, and infectious diseases transmitted by species that have life cycles which are linked to the aquatic environment.
Injuries from encounters with dangerous aquatic organisms are generally sustained by accidentally brushing past a venomous sessile or floating organism when bathing, inadvertently treading on a stingray, weeverfish or sea urchin, unnecessary handling of venomous organisms during seashore exploration, invading the territory of large animals when swimming or at the waterside, swimming in waters used as hunting grounds by large predators or intentionally interfering with, or provoking, danger- ous aquatic organisms.
Disease vectors include mosquitoes, which transmit malaria parasites and the viruses responsible for dengue fever, yellow fever and various types of encephalitis;
and certain species of freshwater snails, which host the larval development of trema- tode parasites of the genus Schistosoma, which can cause a chronic, debilitating and potentially lethal tropical disease known as bilharzia or schistosomiasis in humans.
Preventive measures include asking local health authorities for guidance on the local vector-borne disease situation and risk prevention, wearing protective clothing, using repellents and avoiding skin contact with water in schistosomiasis endemic areas.
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